Technical knowledge · TECHNICAL · REV 2026-10-06
Line array versus point source
A line array is a vertical set of coupled elements used to steer energy over distance. A point source is a cabinet with fixed directivity. Neither is a higher caste. The room chooses.
Definition
The array changes splay between elements to narrow or open coverage. The box count is a result of throw and of the level difference between the first row and the last, not of a symmetrical photo.
A point source covers with the angle of its horn. In a short room it may hit the seats with less energy on the ceiling. In a long room it may leave the back weak or make the front louder than it needs to be.
Why it matters
The wrong shape is paid for twice: once in hardware, once in treating the room the hardware excited. Clarity is measured after aiming and tuning, not when the case is opened.
Technical principle
The vertical control of an array is related to its length versus wavelength. A short array does not behave like a long array at low frequencies. That is physics, not a sales argument.
A good point source holds energy inside a known angle. If the angle is wider than the seats, you are buying reverberation. If it is narrower, you are leaving seats uncovered.
Measurement
A level map
Measure front, middle, and back, standing and seated if the difference matters. A photo of the array is not a map.
Response and time
Tuning delays the fill loudspeakers so two copies of a syllable do not arrive. Measurement shows it. A tired ear on install day is not enough.
Clarity, not only decibels
An even level with energy on the rear wall can still fail STI. Record both.
Units
Decibels and angle
Coverage is discussed as a level difference across the seats and as degrees, not as the phrase “it fills the hall”.
Milliseconds
Delay between fill elements is written as time and distance, not as an undocumented number on a screen.
Design considerations
Draw the seats first
The vertical angle from the loudspeaker to the first row and the last sets the splay or the cabinet choice.
Count what hits a surface
Energy that passes the last head comes back as reverberation. Reducing it is acoustic design, not decoration.
Add subwoofers as a system
Low frequency added without time alignment makes a peak at the front and a hole in the middle.
Typical applications
A long hall or an outdoor stand
An array is a candidate because the distance difference is large. The count is still calculated.
A lecture room twelve metres deep
A point source or a speech column is usually the truer tool. A short array here is ornament.
A balcony
Under-balcony coverage is a separate question. Neither the array nor the front cabinet solves it automatically.
Limitations
The room is stronger than the logo
An excellent array in a bare glass hall does not cancel reverberation.
No cabinet figures here
The manufacturer’s sensitivity and angle are read from the data sheet. This page does not copy them.
Prediction is a start
Coverage software guesses. Measurement after installation decides.
Common mistakes
An even count for the look
Six boxes because the photo is symmetrical, while the calculation asks for four or eight with a different aim.
Hung high with no tilt
Energy goes to the rear wall and the last row hears the reverberation.
Forgetting fills and the stage
The front rows need nearby coverage so the whole array is not turned up for them. The performer needs monitoring that has nothing to do with the array’s shape.
Worked illustration
A room 14 m deep with a low ceiling: the distance difference between the first row and the last is small. An eight-element array finds little steering distance to justify it, and the elements end up close to heads. One or two cabinets with a known angle, plus absorption on the rear wall, are usually clearer. The example is a principle, not a design.
Related parameters
STI
The judgement of speech after the shape is chosen.
Delay
For fill loudspeakers, so arrivals agree.
Cardioid subwoofer
A rear-rejection technique with placement conditions, not a magic button.
Using the number
Calculators and teaching numbers on this site are preliminary. They do not replace an acoustic model, a measurement made to the relevant standard, or the designer's responsibility.
Questions designers and owners ask
Is the array newer and therefore right?
No. Newer is a tool. A short room does not become a stadium because the catalogue changed.
Is a point source too small for a theatre?
Medium theatres worked with aimed cabinets for decades. Weakness comes from a wrong angle or an untuned level.
How many boxes do I need?
From a coverage model that reads the first row, the last row, and the hang height, then from measurement. Not from a handsome even number.
Can DSP rescue the wrong choice?
It sets time, level, and frequency within the cabinet’s limits. It does not narrow a physically wide angle as if it had replaced the horn.
Where do I read on?
The line-array and point-source pages on this site, then the manufacturer’s sheet for the cabinet that will actually be bought.
Technical sources
- Coverage engineering, not a shape catalogue
Prediction software and the manufacturer’s directivity sheets. State their limit: a model is not a measurement.
- IEC 60268-16
If success is intelligible speech, write it as a measurement method, not as an adjective of a device.
- The tuning report
Level maps, delay times, and what was deliberately left outside coverage.
Last editorial review: 2026-10-06. Review means the text was checked, not that a project was measured.
Turn the question into a brief
A study starts from room volume, use, and existing condition, not from a product name. Fill the brief and copy it.
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